III. Read the text and underline the international words.

Gas and oil pipelines are very different in their design and

modes of operation. Gas has a low volumetric heat capacity, warms quickly when compressed, and cools quickly when ex­panded. The quantity of gas transported is greater when the gas is compressed to a high density. However, the gas will get hot when passing through the compressor system. Between compressor stations some expansion and cooling will occur.

Deliberate cooling of the gas is necessary when it is trans­ported through a pipeline buried in the permafrost. The gas in some pipelines is at a pressure as great as 12 megapascals. Af­ter compression, the hot gas must be cooled by refrigeration. A detailed discussion of gas pipeline construction and the envi­ronmental problems associated with its traversal of perma­frost or of active soil layers is found in the city of Williams (1979).

An application was made to the Canadian government in 1974 to build a gas pipeline up the Mackenzie River valley. The Canadian government decided not to allow the Mackenzie valley route, but agreed inistead to build the Alcan gas pipeline parallel to the oil pipeline from Prudhoe Bay to Fairbanks, Alaska; this pipeline was to cross the southern Yukon and follow the Alcan highway to southern Canada, where the pipe­line would branch out to California or to the upper Midwest. (This route avoids the northern Yukon coastal plain, where there is unique wildlife habitat and where the native rights of Eskimos are an important consideration). However, because of a changing oil and gas market, this Alcan gas pipeline has not been built.

Other gas pipeline proposals are under consideration. Among these is a proposal for a pipeline to carry gas from sources in the Canadian Arctic Islands down the west side of Hudson Bay and into eastern Canada. This particular pipeline would need to be installed under the Arctic Ocean between the Boothia Peninsula, Bathurst Island, and Milville Island. The technical challenge of doing this will be enormous. Grooves in the seabed caused by the ploughing of icebergs can occur. Pressure ridges of winter sea ice may scrape the seabed, and floating ice islands may rake the bottom. The pipeline going from the seabed to shore encounters severe problems with wa­ves and floating ice-problems more severe than those encoun­tered with river crossings. However, these technical problems eventually will be solved, and we will have gas pipelines in the Arctic Ocean and in the Antarctic Ocean.

IV. Make up word combinations.

Gas and oil	pnpeliies	Gas and oil pipelines
vricmetolu	heat capacity
uqtantiy	of gas
high	nsietdy
eenmvloimtan	problems
active soil	lrayse
prrcoessom	system
nquuei	wildlife habitat

Дата добавления: 2015-10-21